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2012 450x stock leak jet question

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I just took off the bowl to replace the supposedly stock leak jet size 70 with a 50 to help with the off idle bog. The stock is a 35 on my bike. Anyone have experience with this? Should I still try the 50? All the recommended jetting and air box mods have been done.

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Stock on a 2012 is a #60 (I looked it up); someone already changed it if it's a #35.

 

As long as your that far in, I would check the AP diaphragm and pump circuit to make sure it's working correctly.  You'll also want to check the timing of the squirt.

 

Jim.

Edited by Jim Dettman
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I should add that on my '09, a #55 took care of the bog I had, which was severe enough that it was 50/50 whether it would stall or not.  Stock for the '09 was a #60 as well.

 

A #35 should be more than enough; you need to look at other things in the AP pump circuit.    And BTW, your bog off idle, was that with a slow roll of the idle or just when opening the throttle suddenly?   AP circuit is only for the sudden opening.

 

Jim.

Edited by Jim Dettman

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One other note on the leak jets; smaller means *more* gas for the AP circuit to squirt.   This is the opposite of other Jets.

 

When you activate the AP, this jet controls how fast gas leaks back into the main bowl, so a smaller jet gives the AP more to work with.

 

Jim.

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Jim. Yes it's only when I'm at low rpm and I turn the throttle fast. If I role it on its perfect. My 08 450 R had zero bog no matter how fast I spun the throttle. It it worth looking into a power bowl or quickshot 3?

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Jim. I tried the 50 leak and can't tell any difference between that and the 35. My old wr450 had the exact same problem, but after several rides I learned to ride around the problem. I'm now coming off a 2012 Ktm 300 2 stroke, which had a bog, but it was easy to fix with air screw. I'm an aggressive rider and unless I'm cruising, I'm whipping the throttle a lot.

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A leak jet only supplies fuel to the apump system.

If you are not getting enough fuel to squirt for 1 full second, all the way into the head,  the smaller jet helps.

 

You have to lift up the subframe and visually inspect the squirt in action (dead engine!) to have any idea what the actual problem is.

 

Usually, it is corrosion; of the nozzle (clogged) the cavity (diaphragm no longer works) or the leak jet bypass passage (corroded shut)

 

If it's an older bike, then you have a check valve in the bowl to inspect, and you have to upgrade the linkag spring too.

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As Kah Ran Nee said, there are other things involved besides the leak jet itself.   On a 2012 I would not think you should not be having issues, but if your using fuel with ethanol and not treating it, then you could easily have corrosion of the nozzle.

 

You need to check the AP circuit carefully and make sure that all the passages are clean, including the nozzle in the carb throat.   Again, as Kan Ran Nee said, simplest way is to try it and see if you get a good strong squirt out of the AP.   If it dribbles out of the nozzle and goes no where, then you've got a problem.

 

 The other thing that needs to be checked is the timing of the squirt.   If it's too soon, it splashes on the slide and doesn't make it into the motor quickly enough, leaving you with a bog.   It needs to just miss the slide.

 

 You don't need the o-ring mod, but this video:

 

 

  Gives you an idea of what you should be seeing for the squirt.

 

Jim.

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Thanks for the info. So to check the squirt, I must raise the sub frame correct? Does that mean the exhaust, and shock come off and then pull on subframe to pop air box off carb just in back and leave the front, engine side still connected to boot? Or is there an easier way?

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Seat, tank with shrouds attached, right side panel, muffler, bottom subframe bolts all get removed

Loosen rear carb boot clamp, tilt up subframe, and tighten it in place to stay up with the pivot bolt.

Dead engine whack the throttle, and with a flashlight, watch to see that it sprays all the way into the head, NEVER hitting the slide.

If it hits the slide, your adjust the linkage screw under the throttle wheel cover.

Same for it it is too late, you must adjust so it just barely misses the slide.

If it squirts for longer than 1-1.25 sec, your leak jet is too big.

If it squirts out all crappy and not in a stream, you nozzle is corroded, and must be cleared with very fine steel wire (like from a wound guitar string)

If it squirts too short, you have too large of a leak jet, a hardened pump diaphargm, or you have a corodded pump cavity.

You should inspect the diaphragm to make sure it is a 'late' version with the very short rivet. If it has a long rivet, replace it with the correct one.

 

To re-install the air boot, spray some silicone lubricant on the boot, loosen the front carb boot so you can 'tilt' the carb if needed, and prepare for an excersise in patience.....

I use a very long blunt tire iron to push the boot back on the carb, once the subframe is down.

Lots of light (outside maybe) makes it easier.

Edited by Kah Ran Nee
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Awesome. I'll try it tonight and get back to you.

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Kah ran nee. I just discovered a really easy way to check the accelerator pump.... Take off air filter, get small mirror aim flashlight at mirror. Works perfect, you can see carb clear. Now I just have to wait to have a friend over to twist my throttle since I need two hands for the light and mirror.

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Carbs off I was getting zero squirt. I'm guessing this is the diaphragm and it's all ripped up. How I wonder. Anyone have a part number?.

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a 2012 bike shouldn't have these issues. in my humble opinion I would take off carb and  check completely, could just be a little debris.  if you want to go for glory, I would recommend the r & d power bowl 2 float bowl along with the flexible fuel screw. it is infinitly adjustable without removing the float bowl as the leak jet can be adjusted with a screwdriver from outside of the carb.  besides the suspension and  the twin air filter , I have to say this is the best mod I have done.

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